In the proposed research, we first adapt an existing parent advocacy training program (the Volunteer Advocacy Project, or VAP) to meet the needs of families of youth with autism spectrum disorders (ASD) who are transitioning to adulthood. In a randomly assigned, wait-list control design with 6- and 12-month follow-ups, we then investigate the efficacy of this revised Volunteer Advocacy Project-Transition (or VAP-T). Despite poor outcomes for young adults with ASD and the general inaccessibility of adult services, few transition-focused interventions to assist these young adults and their families are evidence-based. Moreover, most existing approaches either train these youth in social or other skills or endeavor to increase a state or locality's stock of adult disability services. In the proposed research, we adopt a complementary approach, adapting and pilot testing an intervention to increase parents' skills in advocating for their son or daughter with ASD during the transition to adulthood. We propose four Specific Aims: (1) To adapt the VAP to address the needs of transitioning youth with ASD, to test the feasibility and acceptability of the adapted intervention (VAP-T) and of the research design, as well as the fidelity of the VAP-T; (2) To conduct preliminary tests to determine whether participation in the VAP-T is associated with improvements in parents' ability to advocate for their offspring, in service receipt, and in outcomes of the youth with ASD; (3) To conduct preliminary examination of moderators of treatment response; and (4) To produce a VAP-T manual based on results from the proposed research. To investigate these Aims, during Year 1 we will adapt the VAP into the VAP-T, consulting extensively with an Advisory Board comprised of families of youth with ASD, youth themselves, experts in ASD and in the transition to adulthood, and autism and adult-disability service organizations. We will then deliver the intervention to a trial group of parents of young adults with ASD, and use their feedback for further revisions. During Years 2 and 3 of the award, we will conduct a small randomized-controlled trial with a wait-list control group to gather data on feasibility, acceptability, and fidelity of the intervention and of the research design. We will collect data on our primary outcomes of advocacy knowledge, skills, and comfort, as well as on service use and outcomes of the youth with ASD at 6-months and 12-months post-intervention. With this pilot data, we will conduct initial tests of efficacy, as well as gather preliminary data to aid in proposing a larger randomized- controlled trial of the VAP-T, to be delivered at multiple sites. Given the high prevalence of ASD, the preponderance of poor outcomes for adults with ASD, and the remarkable variability in the availability of adult services, developing and testing an intervention that is applicable across the array of adult support landscapes is of critical concern and highly significant, with potential for marked impact on intervention and practice.